import java.util.*;
import java.text.DecimalFormat;
// 格式转换，float 转为 double
public class test{

    public static void main(String args[]){
        Scanner sc = new Scanner(System.in);
        double input = sc.nextDouble();
        DecimalFormat df=new DecimalFormat("0.0000000");
        System.out.println(df.format(Math.pow(input, 1.0/3.0)));

    }
}
